01-22-2013, 04:10 AM | #1 |
WTF does Stage 1 mean?
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Buttoning down the rear end
My boy John took the M out to the track for it's first test and tune of my street tire set-up while I was out of town.
Video from behind: 1:26 is damn good SOW (CCW) time for a stock horsepower car running MPSS tires, PFC brake kit, and Motons. But, as the videos show, driving it still seems to be a point and shoot ordeal unless you want to deal with the cars harsh transition into oversteer. With a base line set-up now out of the way, it's time to start working methods to button down the rear end of the car. The set-up for the car for the trackday was: Front and Rear PFC BBK (street pads) Moton Club Sport (rear coil-over conversion) No Rear Sway Bay Bar The set-up for the next test and tune is going to get a little more extreme: Full TCK mono-ball kit Rear Seat delete Tuner Motorsport solid sub frame bushing New springs and removal of the helper springs from the rear suspension AMS intercooler 18" wheels Hankook RS3's Race pads *os giken LSD Since the stock corner entry understeer issue has been resolved, it's time to play with the camber, tire pressure, and such to find a suitable solution to add some predictability/progressiveness to the rear of the car. Do any of you track junkies have ideas on stabilizing the back end? Last edited by redux; 01-22-2013 at 10:58 AM.. |
01-22-2013, 12:14 PM | #3 |
WTF does Stage 1 mean?
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The 18" setup is already in the works and the camber plates are already on the car. A rear bar may go back on for fine tuning the balance of the car once the back end is close to where I want it. But, it's also on one of the things that makes the car rotate so abruptly.
Last edited by redux; 01-23-2013 at 02:04 PM.. |
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01-23-2013, 01:52 AM | #5 |
WTF does Stage 1 mean?
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265's up front and 295's out back (275's and 285's weren't available at the time of purchase). When I go to 18's, I'll most likely be running 265's squared or something in the 265 front/285 rear range.
Why replace the stock LSD with another LSD? Because an aftermarket solution is another way to fine tune the balance the car. The stock LSD is designed to work in a wide variety of situations, and since to my car is nothing more than a weekend play thing, daily driver versatility is not a requirement. With the aftermarket unit, I'll be able to tailor the handling dynamics and ability to put down the power of the 1 to my specific tastes. |
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01-23-2013, 02:18 PM | #7 |
WTF does Stage 1 mean?
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Roll bar, anti-roll bar, anti-sway bar, the black tube in the picture below. It has many names, and it's been removed from the rear of my car.
Springs will be used to compensate for loss in roll stiffness. |
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01-23-2013, 02:23 PM | #8 | |
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However, I'm very pleased with the diff in my 1M and have no plans to change it. As has been discussed ad nauseum, the 1M is not an easy car to drive on the edge, although steps can be taken to tame it just a bit. Among other things, I'm running camber plates, JRZ dampers and a stiffer E93 M3 front sway. Car still requires quick hands (and feet), but I really dig how it handles. Neil |
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01-23-2013, 03:29 PM | #9 |
WTF does Stage 1 mean?
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The M is not drive is not an easy car to drive fast. Unfortunately, dancing on the edge in this thing is somewhat of an addiction. I'm pretty nifty behind the wheel, but I have no delusions of having Leob like abilities. I would have eventually run out of talent if the car kept it's stock handling traits. Slides at near triple digit speeds are fun, but you can only get away with that for so long.....
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01-23-2013, 04:44 PM | #10 |
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In our experience, larger anti roll bar will only add to the oversteer especially a snap oversteer.
If the main springs don't stay loaded in the inside rear corner during a turn, a snap oversteer may also occur. What spring rates are you running? |
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01-23-2013, 04:58 PM | #11 |
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You said you already removed the rear roll bar and that didn't help reduce oversteer, so why would you go with stiffer springs? That would help roll stiffness but also reduce rear weight transfer. Maybe a small roll bar and softer springs would do the trick.
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01-23-2013, 08:24 PM | #12 | |
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I'm running Swift springs. 7" 392# front/10" 672# rear. Neil |
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01-23-2013, 08:44 PM | #13 |
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01-23-2013, 11:13 PM | #14 |
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I'm a bit surprised with your decision to pull the rear bar. Where are you getting this advice from?
I run one of my Porsches without the rear bar, but I wouldn't expect it to help stabilize the rear in your situation. Running no rear bar means running stiffer rear springs to maintain overall roll compliance. Stiffer rear springs mean you can't put power down as well, causing the back end to step under power. The other thing I could imagine contributing to instability is mismatched shocks. How have you tuned the shocks so far? Have you used principles like these to guide your shock tuning? http://www.ozebiz.com.au/racetech/th...hocktune1.html
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01-24-2013, 01:27 AM | #15 | |||
WTF does Stage 1 mean?
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01-24-2013, 09:22 AM | #16 | ||
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Find a good setup guy to test the car, not just a good driver.
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01-24-2013, 09:44 AM | #17 |
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One thing you might consider doing now is switching to r-comps. Lots of little adjustments needed when you switch and if you are at the level of playing with valving and spring rates then it seems a wasted effort to do so on street tires only to redo everything again once on a proper track tire.
Removing the rear sway seems a blunt way to fix a problem that's likely not solely related. When are you getting the sudden loss of grip? Spring rates and high or low speed valve adj are usually the best avenue of adjustment. Possibly initial static alignment could be an issue too? Changing out factory bushings may help as well. Another source of information would be the M3 track guys; dynamically a bit different but still very similar geometry and hardware. I'm just spit balling here but let us know what you end up with! |
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01-24-2013, 11:36 AM | #18 | |
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Main and helper combo if not done correctly can certainly hurt traction. |
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01-24-2013, 12:22 PM | #19 | ||
WTF does Stage 1 mean?
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The 1M forum seems to be all about HP figures, selling crap, stupid ass "exclusive" polo shirts. So, I made this post just to stir up some actual suspension talk. The transition to oversteer in my car is actually better than it was stock, but not as progressive as an m3. So it's not bad, it's just not where I want it. Quote:
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01-24-2013, 12:33 PM | #20 |
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01-24-2013, 12:34 PM | #21 |
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01-24-2013, 01:36 PM | #22 |
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[QUOTE=redux]
The 1M forum seems to be all about HP figures, selling crap, stupid ass "exclusive" polo shirts. So, I made this post just to stir up some actual suspension talk. The transition to oversteer in my car is actually better than it was stock, but not as progressive as an m3. So it's not bad, it's just not where I want it. [QUOTE] Well said. HP is worthless if you can't utilize it. The 1M's biggest weakness is how abrubtly it transitions to oversteer. Thanks for sharing your quest to resolve this characteristic.
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